In the medical field, observation with an image capture device such as X-ray, CT, MRT, and ultrasonic observational equipment, an endoscope apparatus and the like has been widely performed. Among such image capture devices, the endoscope apparatus has a function and a configuration in which, for example, with an elongated inserting unit inserted in a body cavity of a living body, an image of a view inside the body cavity imaged by an objective optical system laid out on the tip of the inserting unit is captured by a solid-state image sensing device or the like, the image is outputted as an image-captured signal, and the image of the view inside the body cavity is displayed on a monitor or the like based on the image-captured signal. The user observes organs or the like in a body cavity, for example, based on the image of the view inside the body cavity displayed on the monitor or the like. The endoscope apparatus can directly capture an appearance of an alimentary canal mucosa membrane. Thus, the user can integrally observe various findings such as a color of the mucous membrane, a lesion shape, minute structures of a surface of the mucosa membrane and the like, for example.
A capsule endoscope apparatus, for example, has been proposed as an image capture device that can be expected to provide almost the same availability as that of the abovementioned endoscope apparatus. Generally, the capsule endoscope apparatus includes a capsule endoscope which is placed inside the body cavity as it is swallowed by the subject for sending a captured view inside the body cavity to outside as a captured image signal; a receiver which receives that captured image signal sent outside the body cavity and then accumulates the captured image signal received; and an observation device for observing the image of the view inside the body cavity based on the captured image signal accumulated in the receiver.
As a capsule endoscope forming a capsule endoscope apparatus proceeds by peristalsis of alimentary canal, it generally takes several hours or so for the capsule endoscope to be eliminated from an anal after taken into the body cavity from the mouth. Then, as the capsule endoscope keeps on almost always outputting the captured image signal to the receiver after taken into the body cavity until eliminated from the body cavity, the number of still images as frame images accumulated in the receiver is enormous in a dynamic image for several hours, for example. In terms of streamlining observation by a user, a proposal is desired to be done such as to reduce the amount of data of an image as an image processing method for detecting a predetermined image that includes a lesion site such as a bleeding site or the like from the accumulated images performed and then a process for neither displaying nor saving an image other than the predetermined image is performed.
That described in PCT WO 02/073507 A2, for example, is known as such an abovementioned image processing method. A method for detecting abnormality in calorimetric analysis in vivo described in the patent reference is an image processing method including a method for detecting a bleeding site for each divided area of an image based on a distance from each average value in a characteristic space with a color being set as a feature value focusing on a difference between colors of normal mucosa and bleeding site, i.e., a method for detecting a predetermined image that includes a bleeding site as a lesion area.
However, the image processing method described in PCT WO 02/073507 A2 has a problem described below.
Generally speaking, in an alimentary canal, image capturing is not always performed only on the image of the surface of mucosa membrane of a living body, but image capturing is performed in a state where both of the image of foreign bodies such as stool, bubbles, mucosal fluid, food debris, or the like, and the image of the surface of mucosa membrane of a living body exist. Therefore, in the image processing method described in PCT WO 02/073507 A2 which does not take the existence of foreign bodies into consideration, there are possibilities of erroneously detecting a normal mucosa membrane as a bleeding site due to the foreign bodies, and of detecting an image in which an image of the foreign bodies occupies the most part of the whole image. As a result, in a case where an observation using the image processing method described in PCT WO 02/073507 A2 is performed, there is a problem of deterioration in observation efficiency attributed to deterioration in accuracy of detecting a lesion area.
The present invention is conceived in view of the above-described points, and an object of the present invention is to provide an image processing apparatus and an image processing method capable of improving observation efficiency by a user.